Large quantities of waste products are generated at a saw mill and a pulp and paper mill and many of those products cannot be disposed of easily. Pulp and paper sludges are particularly difficult to dispose of. Such sludges, because of their high moisture content, cannot be incinerted without first being dried. The cost of drying them usually far exceeds any savings derived from incinerating them as an alternative source of heat or energy. For this reason other methods of disposal are generally used.
The most common method of disposal of pulp and paper sludges is at a landfill site. Less commonly it is disposed of by spreading it over waste land. Existing landfill and land spreading sites are being rapidly depleted because of the large quantities of sludge generated by mills. New sites are not becoming available at the rate required to meet the demand of mills because of environmental concerns.